WO2019004257A1 - Ethylene-vinyl alcohol copolymer composition for melt molding, pellet and multilayer structure - Google Patents

Abstract

As an ethylene-vinyl alcohol copolymer and a multilayer structure which are suppressed in coloring after heating, the present invention provides an ethylene-vinyl alcohol copolymer composition for melt molding, which is an ethylene-vinyl alcohol copolymer resin composition containing an ethylene-vinyl alcohol copolymer (A), an alkaline earth metal compound (B) and an iron compound (C), and which is configured such that the content of the iron compound (C) is from 0.01 ppm to 20 ppm in terms of metal relative to the weight of the ethylene-vinyl alcohol copolymer composition.

Description

Ethylene-vinyl alcohol copolymer composition for melt molding, pellet and multilayer structure

The present invention relates to a melt-forming EVOH resin composition, a pellet and a multilayer structure mainly comprising ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as "EVOH resin"), More specifically, the present invention relates to a melt-forming EVOH resin composition, a pellet, and a multilayer structure in which coloring after heating is suppressed.

EVOH resin is excellent in transparency, gas barrier properties such as oxygen, odor retention, solvent resistance, oil resistance, mechanical strength, etc., and is formed into a film, a sheet, a bottle, etc., food packaging material, pharmaceutical packaging material, It is widely used as various packaging materials such as industrial chemical packaging materials and agrochemical packaging materials.

However, EVOH resin has a relatively active hydroxyl group in the molecule, so even in the extruder with almost no oxygen, oxidation / crosslinking reaction occurs in the high temperature melt state, and problems such as coloring and gelation occur. Tend. In order to solve such problems, for example, in Patent Document 1, a saponified ethylene-vinyl acetate copolymer (A) having an ethylene content of 20 to 60 mol% and a saponification degree of 90 mol% or more, acetic acid (B) And magnesium acetate and / or calcium acetate (C), and the content of (B) is 0.05 parts by weight or less with respect to 100 parts by weight of (A), and the content of (C) is equivalent to metal The resin composition is characterized in that it is 0.001 to 0.02 parts by weight with respect to 100 parts by weight of (A), and it is excellent in long run property at the time of melt molding, and has fish eyes, streaks and coloring A molded product which is small and excellent in appearance is obtained, and the odor is reduced even when the molded product is made into a laminate, and the interlayer of the laminate is obtained even after secondary processing such as drawing and deep drawing. Disclosed is a resin composition which is also excellent in adhesion.

Japanese Patent Application Laid-Open No. 11-106592

In recent years, with the diversification of feed block / die shapes in the molding apparatus, various functionalization requests such as thinning of the multilayer structure in the final product and increase in the number of layers, there is a tendency for the molding apparatus to have higher functions. On the other hand, there is a tendency for the resin to be thermally degraded in the complicated molding apparatus due to high functionalization, causing coloration and the like to reduce the productivity of the product, and a further improvement has been demanded.

As a result of intensive studies in view of the above situation, the present inventors have found that a coloring inhibiting effect can be obtained at the time of heating by using an alkaline earth metal compound in combination with a trace amount of iron compound as a compounding agent of EVOH resin. .

That is, the present invention is an EVOH resin composition containing EVOH resin (A), alkaline earth metal compound (B) and iron compound (C), wherein the content of iron compound (C) is EVOH resin composition The first aspect of the EVOH resin composition for melt molding is 0.01 to 20 ppm in terms of metal per weight of the pellets, and the second aspect of the pellet is a pellet comprising the EVOH resin composition for melt molding I assume. Furthermore, this invention makes the multilayer structure provided with the layer which consists of the said EVOH resin composition for melt molding the 3rd summary.

The EVOH resin composition for melt molding of the present invention is an EVOH resin composition containing an EVOH resin (A), an alkaline earth metal compound (B) and an iron compound (C), and containing an iron compound (C) Since the amount is 0.01 to 20 ppm in terms of metal per weight of the EVOH resin composition, coloring at the time of heating such as melt molding can be suppressed.

Further, among the present invention, in particular, when the content of the alkaline earth metal compound (B) is 0.1 to 500 ppm in terms of metal per weight of the EVOH resin composition, the time of heating such as melt molding is further enhanced. Coloring can be suppressed.

And, among the present invention, particularly, the weight ratio of the metal conversion content of the alkaline earth metal compound (B) to the metal conversion content of the iron compound (C) is 0.005 to 50000. The coloration at the time of heating such as melt molding can be further suppressed.

Furthermore, among the present invention, in particular, when the alkaline earth metal compound (B) is a carboxylate, coloration at the time of heating such as melt molding can be further suppressed.

In addition, since pellets made of the EVOH resin composition for melt molding of the present invention have a good coloring suppressing effect at the time of heating such as melt molding, they can be used as various molded articles by melt molding, for example, as packaging materials for food, medicine, agricultural chemicals It can be used suitably.

And the multilayer structure provided with the layer which consists of the EVOH resin composition for melt molding of this invention is especially useful as packaging materials, such as a foodstuff, medicine, and an agrochemical.

Hereinafter, although the configuration of the present invention will be described in detail, these are merely examples of preferred embodiments, and the present invention is not limited to these contents.

The EVOH resin composition used for the melt-molding EVOH resin composition of the present invention is mainly composed of the EVOH resin (A), and contains an alkaline earth metal compound (B) and an iron compound (C). In the EVOH resin composition for melt molding of the present invention, the base resin is EVOH resin (A). That is, the content of EVOH resin (A) in the EVOH resin composition is usually 70% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, and particularly preferably 95% by weight It is above. Hereinafter, the EVOH resin composition for melt molding of the present invention may be referred to as "EVOH resin composition".
Each component will be described below.

[EVOH resin (A)]
The EVOH resin (A) used in the present invention is generally a resin obtained by saponifying an ethylene-vinyl ester copolymer which is a copolymer of ethylene and a vinyl ester monomer, and is non-water soluble It is a thermoplastic resin. From the economical point of view, vinyl acetate is generally used as the vinyl ester monomer.

As a polymerization method of ethylene and a vinyl ester type monomer, although it can carry out using publicly known arbitrary polymerization methods, for example, solution polymerization, suspension polymerization, emulsion polymerization, etc., methanol is generally used as a solvent. Solution polymerization is used. Saponification of the obtained ethylene-vinyl ester copolymer can also be carried out by a known method.

The EVOH resin (A) thus produced is mainly composed of a structural unit derived from ethylene and a vinyl alcohol structural unit, and contains a slight amount of vinyl ester structural unit remaining without being saponified.

As the above-mentioned vinyl ester-based monomer, vinyl acetate is typically used from the viewpoint of good market availability and high efficiency of treatment of impurities at the time of production. Other vinyl ester monomers include, for example, vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl versatate and the like. Aliphatic vinyl esters, aromatic vinyl esters such as vinyl benzoate and the like can be mentioned, and aliphatic vinyl esters having 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms are generally used. Can. These are usually used alone, but two or more species may be used simultaneously as required.

The content of the ethylene structural unit in the EVOH resin (A) can be controlled by the pressure of ethylene at the time of copolymerizing the vinyl ester monomer and ethylene, and is usually 20 to 60 mol%, preferably 25 to 50 mol. %, Particularly preferably 25 to 35 mol%. When the content is too low, the gas barrier properties under high humidity and the stretchability tend to decrease, and when the content is too high, the gas barrier properties tend to decrease.
In addition, content of this ethylene structural unit can be measured based on ISO14663.

The degree of saponification of the vinyl ester component in EVOH resin (A) is the amount of saponification catalyst (usually an alkaline catalyst such as sodium hydroxide is used) when saponifying ethylene-vinyl ester copolymer, temperature And 90 to 100 mol%, preferably 95 to 100 mol%, and particularly preferably 99 to 100 mol%. If the degree of saponification is too low, the gas barrier properties, thermal stability, moisture resistance and the like tend to decrease.
The degree of saponification of the EVOH resin (A) can be measured based on JIS K 6726 (however, the EVOH resin is used as a solution uniformly dissolved in water / methanol solvent).

The melt flow rate (MFR) (210 ° C., load 2160 g) of the EVOH resin (A) is usually 0.5 to 100 g / 10 min, preferably 1 to 50 g / 10 min, particularly preferably 3 to It is 35 g / 10 min. If the MFR is too large, the stability during film formation tends to be impaired, and if it is too small, the viscosity tends to be too high and melt extrusion tends to be difficult.
The MFR is an index of the degree of polymerization of the EVOH resin, and can be adjusted by the amount of the polymerization initiator or the amount of the solvent when the ethylene and the vinyl ester monomer are copolymerized.

In the EVOH resin (A) used in the present invention, structural units derived from the comonomers shown below are further included in a range not inhibiting the effect of the present invention (for example, 10 mol% or less of the EVOH resin (A)) It may be done.
As the above comonomers, olefins such as propylene, 1-butene and isobutene, 3-buten-1-ol, 3-butene-1,2-diol, 4-penten-1-ol, 5-hexene-1,2 Hydroxy group-containing α-olefins such as diols and derivatives thereof such as esters and acylates thereof; hydroxyalkyl vinylidenes such as 2-methylenepropane-1,3-diol, 3-methylenepentane-1,5-diol; Hydroxyalkylvinylidene diacetates such as 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, 1,3-dibutyryloxy-2-methylenepropane; acrylic acid, methacrylic acid , Crotonic acid, (anhydride) phthalic acid, (anhydride) maleic acid, (anhydride) itaconic acid, etc. Saturated acids or salts thereof or mono- or dialkyl esters having 1 to 18 carbon atoms; acrylamide, N-alkyl acrylamides having 1 to 18 carbon atoms, N, N-dimethyl acrylamide, 2-acrylamidopropanesulfonic acid or salts thereof, acrylamidopropyl Acrylamides such as dimethylamine or its acid salt or its quaternary salt; methacrylamide, N-alkyl methacrylamide having 1 to 18 carbon atoms, N, N-dimethyl methacrylamide, 2-methacrylamidopropane sulfonic acid or its salt, Methacrylamide such as methacrylamidopropyldimethylamine or its acid salt or its quaternary salt; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, etc. Acrylonitrile Vinyl cyanides such as tolyl and methacrylonitrile; vinyl ethers such as alkyl vinyl ethers having 1 to 18 carbon atoms, hydroxyalkyl vinyl ethers and alkoxyalkyl vinyl ethers; vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, vinyl bromide and the like Halogenated vinyl compounds; vinylsilanes such as trimethoxyvinylsilane; halogenated allyl compounds such as allyl acetate and allyl chloride; allyl alcohols such as allyl alcohol and dimethoxyallyl alcohol; trimethyl- (3-acrylamido-3-dimethyl) Examples include comonomers such as propyl) -ammonium chloride and acrylamido-2-methylpropane sulfonic acid. These can be used alone or in combination of two or more.

In particular, an EVOH resin having a primary hydroxyl group in a side chain is preferable in that the secondary formability becomes good while maintaining the gas barrier property, and in particular, an EVOH resin obtained by copolymerizing a hydroxy group-containing α-olefin is preferable. In particular, EVOH resins having a 1,2-diol structure in the side chain are preferred.
In particular, in the case of an EVOH resin having a primary hydroxyl group in the side chain, the content of the structural unit derived from the monomer having a primary hydroxyl group is usually 0.1 to 20 mol% of the EVOH resin, and further 0.5 to 0.5 15 mol%, in particular 1 to 10 mol% is preferred.

The EVOH resin (A) used in the present invention may be one that has been "post-modified" such as urethanization, acetalization, cyanoethylation, oxyalkylenation and the like.

Furthermore, the EVOH resin (A) used in the present invention may be a mixture with other different EVOH resins, and as such other EVOH resins, those having different saponification degrees, those having different polymerization degrees, What has a different copolymerization component etc. can be mentioned.

[Alkaline earth metal compound (B)]
The EVOH resin composition of the present invention is a resin composition containing an alkaline earth metal compound (B), and the amount of the alkaline earth metal compound (B) is usually 1 to 1000 ppm by weight based on the entire EVOH resin composition. It is contained. The content of the above-mentioned alkaline earth metal compound (B) is preferably 10 to 800 ppm, particularly preferably 50 to 500 ppm.
The content of the alkaline earth metal compound (B) in terms of metal weight is usually 0.1 to 500 ppm, preferably 0.5 to 300 ppm, more preferably 1 to 200 ppm, based on the total weight of the EVOH resin composition. Particularly preferred is 2 to 150 ppm.
When the content is too large, the thermal stability tends to decrease, and when the content is too small, the moldability of the EVOH resin composition tends to decrease.

In addition, the EVOH resin composition used as the reference | standard of the content rate of the said alkaline-earth metal compound (B) is an EVOH resin (A), an alkaline-earth metal compound (B), an iron compound (C), and it mix | blends as needed. An EVOH resin composition as a final product containing various additives and the like.

Examples of the alkaline earth metal species of the alkaline earth metal compound (B) used in the present invention include beryllium, magnesium, calcium, strontium, barium and radium. These can be used alone or in combination of two or more. Among these, magnesium and calcium are preferable in terms of market availability and economy.

Examples of the alkaline earth metal compound (B) used in the present invention include the salts, oxides and hydroxides of the above-mentioned alkaline earth metals. Among them, alkaline earth metal oxides or alkaline earth metal salts are preferable in terms of economy and dispersibility, and alkaline earth metal salts are particularly preferable. Examples of the above-mentioned alkaline earth metal oxide include magnesium oxide and calcium oxide. Examples of the above-mentioned alkaline earth metal salts include inorganic salts such as carbonates, hydrogencarbonates, phosphates, borates, sulfates and chlorides, and carboxylates.
The alkaline earth metal compound (B) used in the present invention preferably excludes layered inorganic compounds such as montmorillonite and double salts such as hydrotalcite from the viewpoint of economy and dispersibility.

Among them, carboxylates are preferable in that they are excellent in the viscosity lowering effect at the time of heating. Such carboxylic acid salts include saturated or unsaturated carboxylic acid salts. For example, monovalent carboxylic acids such as acetate, butyrate, propionate, enanthate, caprate, laurate, palmitate, stearate, 12 hydroxystearate, behenate, montanate and the like Examples thereof include acid salts, oxalates, malonates, succinates, adipates, suberates, divalent carboxylates such as sebacates, and the like. These can be used alone or in combination of two or more. From the viewpoint of market availability, preferred are linear saturated carboxylic acid salts, and more preferred are monovalent carboxylic acid salts.
The carbon number of the anion of such a carboxylate is usually 2 to 25, preferably 2 to 22 and particularly preferably 6 to 20 in terms of productivity.
Further, the content of the alkaline earth metal compound when using a plurality of alkaline earth metal compounds (B) is the total content of all the alkaline earth metal compounds (B).

And, as the form of the alkaline earth metal compound (B), for example, solid form (powder, fine powder, flakes, etc.), semi-solid form, liquid form, paste form, solution form, emulsion form (water dispersion liquid) The thing of arbitrary properties, such as, can be used. Among them, powder is preferable.

The content of the alkaline earth metal compound (B) in the EVOH resin composition of the present invention is, for example, a solution obtained by acid treatment of the heat-ashed EVOH resin composition of the present invention with hydrochloric acid or the like. A solution made by adding pure water to a constant volume is used as a test solution, and can be measured with an atomic absorption photometer.

[Iron compound (C)]
The EVOH resin composition of the present invention is characterized by containing the EVOH resin (A), the alkaline earth metal compound (B) and the iron compound (C), and the compounding amount of the iron compound (C) is a specific trace amount It is. It has been found that adopting this configuration suppresses the coloration of the EVOH resin composition after heating.

In general, it is known that when an alkaline earth metal salt is blended into an EVOH resin, it exhibits a viscosity-decreasing tendency with time during heating. Although the mechanism is not clear, by blending an alkaline earth metal compound, the EVOH resin composition becomes basic, any anion becomes a nucleophile, and the hydrogen attached to the main chain carbon of the EVOH resin is extracted, etc. It is presumed that this causes chain decomposition reaction and the main chain of EVOH resin is cut. In the coloring after heating of the EVOH resin, a double bond structure is formed in the main chain of the EVOH resin during the above reaction, and this structure again becomes the reaction starting point to cause dehydration reaction etc., and a polyene structure is formed in the main chain of the EVOH resin. It is presumed to be formed.

In the present invention, such coloring is suppressed by using the alkaline earth metal compound (B) in combination with a specific trace amount of the iron compound (C). That is, iron is stable as a trivalent ion, and even if it is a trace amount, it stabilizes by coordinating to the double bond of the main chain of EVOH resin as described above to form a chelate, etc. to form a polyene structure. It is presumed that it is suppressing.
In the present invention, it has been unexpectedly found that the combined use of the alkaline earth metal compound (B) and the iron compound (C) enhances the temporal viscosity reduction effect at the time of heating.

In the EVOH resin composition of the present invention, the content of the iron compound (C) is 0.01 to 20 ppm in terms of metal per weight of the EVOH resin composition. It is preferably 0.03 to 8 ppm, particularly preferably 0.05 to 3 ppm, particularly preferably 0.05 to 0.8 ppm.
When the content of the iron compound (C) is too small, the coloration suppressing effect after heating tends to decrease, and when too large, the formed product tends to be colored.

Here, the content of the iron compound (C) is measured by the following method.
<Analysis of iron compound (C)>
A ground product of 0.5 g of EVOH resin composition pellets is subjected to an incineration treatment at 650 ° C. for 1 hour in an infrared heating furnace under an oxygen stream, and the ash content is acid-dissolved and made up to volume with pure water to obtain a sample solution. This solution is measured by ICP-MS standard addition method using an Agilent Technologies ICP mass spectrometer Model 7500ce.

The iron compound (C) is present in the EVOH resin composition, for example, as an oxide, hydroxide, chloride or iron salt, in an ionized state, or as a resin or other ligand. It may be present in the form of a complex in which it interacts with Examples of the oxide include ferric oxide, tetrairon tetraoxide, iron suboxide and the like. Examples of the chloride include ferrous chloride, ferric chloride and the like. Examples of the hydroxide include ferrous hydroxide, ferric hydroxide and the like. Examples of the iron salt include inorganic salts such as iron phosphate and iron sulfate, and organic salts such as carboxylic acid (acetic acid, butyric acid, stearic acid and the like) and iron. These can be used alone or in combination of two or more.

The iron compound (C) is preferably water soluble from the viewpoint of dispersibility in the EVOH resin composition. The molecular weight is usually 100 to 10000, preferably 100 to 1000, and particularly preferably 100 to 500, from the viewpoint of dispersibility and productivity.

The weight ratio of the content of the alkaline earth metal compound (B) to the metal equivalent content of the iron compound (C) in the EVOH resin composition used in the present invention is usually 0.2 to 50000, preferably 1 It is at most 10000, particularly preferably 50 to 8000, particularly preferably 800 to 5000.
The weight ratio of the metal conversion content of the alkaline earth metal compound (B) to the metal conversion content of the iron compound (C) is usually 0.005 to 50000, preferably 1 to 30000. Particularly preferably, it is 10 to 10000, and particularly preferably 30 to 5000.
When the above value is too large, the heat stability tends to be impaired, and when it is too small, the molded article tends to be colored.

[Other thermoplastic resin]
In the EVOH resin composition used in the present invention, a thermoplastic resin other than the EVOH resin (A) is in a range not inhibiting the effects of the present invention (for example, usually 30% by weight or less of the EVOH resin composition, preferably 20% by weight) The following can be contained, particularly preferably 10% by weight or less.
A well-known thermoplastic resin can be used as another thermoplastic resin. For example, specifically, polyamide resin, polyolefin resin, polyester resin, polystyrene resin, polyvinyl chloride resin, polycarbonate resin, polyacrylic resin, ionomer, ethylene-acrylic acid copolymer, ethylene- Acrylic ester copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, polyvinylidene chloride, vinyl ester resin, polyester elastomer, polyurethane elastomer, chlorinated polyethylene, chlorinated polypropylene, etc. . These can be used alone or in combination of two or more.

[Other ingredients]
Moreover, the EVOH resin composition of this invention may contain the compounding agent generally mix | blended with EVOH resin in the range which does not inhibit the effect of this invention. For example, plasticizers (for example, aliphatic polyhydric alcohols such as ethylene glycol, glycerin, hexanediol, etc.), oxygen absorbers [for example, inorganic oxygen absorbers such as aluminum powder, potassium sulfite, titanium oxide photocatalyst, etc .; ascorbic acid, The fatty acid ester and metal salts other than alkaline earth metals, hydroquinone, gallic acid, polyhydric phenols such as hydroxyl group-containing phenol aldehyde resin, bis-salicylic aldehyde-imine cobalt, tetraethylenepentamine cobalt, cobalt-Schiff base complex , Coordination complexes of nitrogen-containing compounds such as porphyrins, macrocyclic polyamine complexes and polyethyleneimine-cobalt complexes with transition metals other than iron, terpene compounds, reaction products of amino acids and hydroxyl group-containing reducing substances, triphenyl Organic compounds such as methyl compounds Compound-based oxygen absorbent; coordination bond of nitrogen-containing resin and transition metal other than iron (for example, combination of methyl xylylene diamine (MXD) nylon and cobalt), transition metal other than tertiary hydrogen-containing resin and iron (Eg, a combination of polypropylene and cobalt), a blend of a carbon-carbon unsaturated resin and a transition metal other than iron (eg, a combination of polybutadiene and cobalt), a photo-oxidizable resin (eg, polyketone), Anthraquinone polymers (for example, polyvinyl anthraquinone) or the like, and further, a photoinitiator (such as benzophenone), a peroxide scavenger (such as a commercially available antioxidant) or a deodorant (such as activated carbon) added to these compounds Etc.], heat stabilizers, light stabilizers, UV absorbers, colorants, antistatic agents, surfactants (but as lubricants) Excluding shall), antimicrobials, antiblocking agents, may be blended such as fillers (e.g. inorganic fillers and the like). These compounds can be used alone or in combination of two or more.

[Method of producing EVOH resin composition]
Examples of the method for producing the EVOH resin composition of the present invention include known methods such as a dry blending method, a melt mixing method, a solution mixing method, and an impregnation method, and these may be arbitrarily combined.

Examples of the dry blending method include a method of dry blending (i) EVOH resin (A) pellet, and at least one of an alkaline earth metal compound (B) and an iron compound (C) using a tumbler or the like. .

As a melt-mixing method, for example, (ii) EVOH resin (A) pellets, and a dry blend of at least one of an alkaline earth metal compound (B) and an iron compound (C) are melt-kneaded, And (iii) at least one of the alkaline earth metal compound (B) and the iron compound (C) is added to the molten EVOH resin (A) and melt-kneaded to obtain pellets or molded articles. Be

As a solution mixing method, for example, a solution is prepared using a commercially available EVOH resin (A) pellet, and at least one of an alkaline earth metal compound (B) and an iron compound (C) is blended therein, A method of solidifying, pelletizing, solid-liquid separation and drying, or (v) an alkaline earth metal compound (B / B solution) in a uniform solution (water / alcohol solution etc.) of EVOH resin in the production process of EVOH resin (A) And / or iron compound (C), and then coagulated and formed into pellets, solid-liquid separated, and dried.

As the impregnation method, for example, (vi) EVOH resin (A) pellets are brought into contact with an aqueous solution containing at least one of an alkaline earth metal compound (B) and an iron compound (C), and the EVOH resin (A) is contained in the pellet. After containing at least one of the alkaline earth metal compound (B) and the iron compound (C), and drying.

In the present invention, it is possible to combine the different methods described above. Among them, the melt mixing method is preferable, and in particular, the method (ii) is preferable, from the viewpoint that the resin composition in which the productivity and the effect of the present invention are more remarkable can be obtained.

In addition, the shape of the EVOH resin composition pellet of this invention obtained by said each method and EVOH resin (A) pellet used by each method is arbitrary. For example, there are spheres, ovals, cylinders, cubes, and cuboids, but they are usually ovals or cylinders, and their sizes are ovals from the viewpoint of convenience when they are used as molding materials later. In this case, the minor diameter is usually 1 to 10 mm, preferably 2 to 6 mm, more preferably 2.5 to 5.5 mm, and the major diameter is usually 1.5 to 30 mm, preferably 3 to 20, more preferably It is 3.5 to 10 mm. In the case of a cylindrical shape, the diameter of the bottom is usually 1 to 6 mm, preferably 2 to 5 mm, and the length is usually 1 to 6 mm, preferably 2 to 5 mm.

In addition, as the iron compound (C) used in each of the above methods, as described above, a water-soluble iron compound is preferably used, for example, ferric oxide, ferric oxide, iron suboxide, etc. Oxides, chlorides such as ferrous chloride and ferric chloride, hydroxides such as ferrous hydroxide and ferric hydroxide, inorganic salts such as iron phosphate and iron sulfate, and carboxylic acids (acetic acid, Examples include iron salts such as organic salts such as butyric acid and stearic acid etc. iron. As described above, the iron compound (C) is present in the EVOH resin composition as the above-mentioned salt, in the ionized state, or in the state of the complex using the resin or other compound as a ligand. May exist.

In addition, as an aqueous solution containing an iron compound to be used in the method (vi), it is possible to use an aqueous solution of the iron compound or an iron material eluted by immersing the steel material in water containing various agents. Can. In that case, the content (in terms of metal) of the iron compound (C) in the EVOH resin composition is controlled by the concentration of the iron compound in the aqueous solution in which the EVOH resin (A) pellet is immersed, the immersion temperature, the immersion time, etc. It is possible. The immersion temperature and immersion time are usually 0.5 to 48 hours, preferably 1 to 36 hours, and the immersion temperature is usually 10 to 40 ° C., preferably 20 to 35 ° C.
The EVOH resin composition pellets are solid-liquid separated by a known method and dried by a known drying method. As the drying method, various drying methods can be adopted, and either stationary drying or fluid drying may be used. Moreover, it can also carry out combining these.

The moisture content of the EVOH resin composition of the present invention is usually 0.01 to 0.5% by weight, preferably 0.05 to 0.35% by weight, particularly preferably 0.1 to 0.3% by weight It is.

The water content of the EVOH resin composition of the present invention is measured and calculated by the following method.
The weight before drying (W1) of the EVOH resin composition is weighed by an electronic balance, dried in a hot air drier at 150 ° C. for 5 hours, and the weight (W2) after allowed to cool in a desiccator for 30 minutes is weighed. Calculated from the equation.
Moisture content (% by weight) = [(W1-W2) / W1] × 100

The pellet of the EVOH resin composition thus obtained can be subjected to melt molding as it is, but from the point of stabilizing feedability at the time of melt molding, a known lubricant is attached to the surface of the pellet. Is also preferred. Types of lubricants include higher fatty acids (eg, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, etc.), higher fatty acid esters (methyl esters of higher fatty acids, isopropyl esters, butyl esters, octyl esters, etc.) , Higher fatty acid amides (eg, saturated higher fatty acid amides such as lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, etc .; unsaturated higher fatty acid amides such as oleic acid amide, erucic acid amide, ethylene bis Stearic acid amide, ethylene bis oleic acid amide, ethylene bis erucic acid amide, bis higher fatty acid amides such as ethylene bis lauric acid amide, etc., low molecular weight polyolefins (eg, low molecular weight polyethylene having a molecular weight of about 500 to 10,000, Low molecular weight polypropylene, or an acid modified products), higher alcohols, ester oligomer, such as ethylene fluoride resins. The content of such a lubricant is usually 5% by weight or less, preferably 1% by weight or less of the EVOH resin composition.

The EVOH resin composition of the present invention is prepared as various forms of EVOH resin composition such as pellets, powder or liquid, and provided as a material for melt molding of various molded articles. In addition, the resin composition obtained by mixing resin other than EVOH resin (A) used for EVOH resin composition of this invention is also contained in EVOH resin composition of this invention.

And as such a molded product, a multilayer structure having a layer molded using the EVOH resin composition pellet of the present invention, including a single layer film molded using the EVOH resin composition pellet of the present invention It can be put to practical use.

[Multilayer structure]
The multilayer structure obtained by using the EVOH resin composition for melt molding of the present invention has a layer composed of the above EVOH resin composition. The layer containing the EVOH resin composition obtained by using the EVOH resin composition for melt molding of the present invention (hereinafter simply referred to as "EVOH resin composition layer") is a thermoplastic resin other than the EVOH resin composition of the present invention. By further laminating it on another base material (hereinafter, the resin used as the base material may be abbreviated as “base resin”) having as a main component, to further impart strength or to an EVOH resin composition layer Can be protected from the influence of moisture etc., or given other functions.

Examples of the base resin include linear low density polyethylene, low density polyethylene, ultra low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-propylene (block and random) copolymer, ethylene-α-olefin Polyethylene resins such as (C4 to C20 α-olefin) copolymers, polypropylene, polypropylene resins such as polypropylene and propylene-α-olefin (C4 to C20 α-olefin) copolymers, polybutene, polypentene And (unmodified) polyolefin resins such as polycycloolefin resin (polymer having cyclic olefin structure and at least one of main chain and side chain), and graft modification of these polyolefins with unsaturated carboxylic acid or ester thereof Unsaturated carboxylic acid modified polyolefin tree And other polyolefin resins in the broad sense, including modified olefin resins, ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, polyester resins, polyamide resins (co (Including polymerized polyamide), polyvinyl chloride, polyvinylidene chloride, acrylic resin, polystyrene resin, vinyl ester resin, polyester elastomer, polyurethane elastomer, polystyrene elastomer, halogenated polyethylene, chlorinated polyethylene, chlorinated polypropylene etc. Polyolefins, aromatic or aliphatic polyketones and the like can be mentioned.

Among these, polyamide resins, polyolefin resins, polyester resins, and polystyrene resins, which are hydrophobic resins, are preferable, and more preferably, polyethylene resins, polypropylene resins, polycyclic olefin resins, and unsaturated thereof. It is polyolefin resin, such as carboxylic acid modified polyolefin resin.

The layer structure of the multilayer structure is a (a1, a2,...) Of the EVOH resin composition layer obtained from the EVOH resin composition for melt molding of the present invention, b (b1, b2,. · ·), A / b, b / a / b, a / b / a, a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a Any combination such as / b1 / a / b1 / b2 is possible. Further, a mixture of the above EVOH resin composition and a thermoplastic resin other than the EVOH resin composition of the present invention, which is obtained by re-melt molding an end portion or a defective product or the like generated in the process of producing the multilayer structure. When the recycle layer containing is R, b / R / a, b / R / a / b, b / R / a / R / b, b / a / R / a / b, b / R / a / R It is also possible to use / a / R / b or the like. The number of layers in the multilayer structure is usually 2 to 15, preferably 3 to 10 in total. In the above layer configuration, an adhesive resin layer containing an adhesive resin may be interposed between each layer, as needed.

A well-known thing can be used as said adhesive resin, and what is necessary is just to select suitably according to the kind of thermoplastic resin used for base-material resin "b". Typically, there can be mentioned a modified polyolefin polymer containing a carboxyl group obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin by an addition reaction, a graft reaction or the like. Examples of the modified polyolefin polymer containing a carboxyl group include maleic anhydride graft modified polyethylene, maleic anhydride graft modified polypropylene, maleic anhydride graft modified ethylene-propylene (block and random) copolymer, and maleic anhydride Examples thereof include graft modified ethylene-ethyl acrylate copolymer, maleic anhydride graft modified ethylene-vinyl acetate copolymer, maleic anhydride modified polycyclic olefin resin, and maleic anhydride graft modified polyolefin resin. And 1 type, or 2 or more types of mixtures chosen from these can be used.

When an adhesive resin layer is used between the EVOH resin composition layer obtained from the EVOH resin composition for melt molding of the present invention and a base resin layer in a multilayer structure, the adhesive resin layer is an EVOH resin composition It is preferable to use an adhesive resin excellent in hydrophobicity because it is located on both sides of the layer.

The above-mentioned base resin and adhesive resin are plastic as conventionally known in the range (for example, 30% by weight or less, preferably 10% by weight or less based on the whole resin) which does not disturb the purpose of the present invention It may contain an agent, filler, clay (montmorillonite, etc.), coloring agent, antioxidant, antistatic agent, lubricant, core material, antiblocking agent, wax and the like. These can be used alone or in combination of two or more.

Lamination of the EVOH resin composition layer obtained by using the EVOH resin composition for melt molding of the present invention with the above-mentioned base resin layer (including the case of interposing an adhesive resin layer) is carried out by a known method. Can. For example, a method of melt extruding a base resin on a film, sheet or the like of an EVOH resin composition, a method of melt extruding an EVOH resin composition on a base resin layer, coextrusion of the EVOH resin composition and a base resin A method of dry laminating the EVOH resin composition (layer) and the base resin (layer) using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester compound or a polyurethane compound, on the base resin And a method of removing the solvent after applying the solution of the EVOH resin composition to the above. Among these, a coextrusion method is preferable in consideration of cost and environment.

The multilayer structure as described above is then subjected to a (heating) stretching treatment as required. The stretching treatment may be either uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Further, as the stretching method, a roll stretching method, a tenter stretching method, a tubular stretching method, a stretch blow method, a vacuum pressure air forming, or the like having a high stretch ratio can be employed. The stretching temperature is selected from the range of about 40 to 170 ° C., preferably about 60 to 160 ° C., at a temperature near the melting point of the multilayer structure. When the stretching temperature is too low, the stretchability becomes poor, and when it is too high, it becomes difficult to maintain a stable stretched state.

In addition, you may heat-set for the purpose of providing dimensional stability after extending | stretching. The heat setting can be carried out by a known means. For example, the stretched film is subjected to heat treatment usually at 80 to 180 ° C., preferably at 100 to 165 ° C., usually for about 2 to 600 seconds while maintaining tension. Moreover, when using the multilayer stretched film obtained from the EVOH resin composition for melt molding of the present invention as a film for shrinking, the above-mentioned heat setting is not performed to impart heat shrinkability, and for example, after stretching The film may be cooled and fixed by applying cold air.

In some cases, it is also possible to obtain a cup- or tray-like multilayer container using the above-described multilayer structure. In that case, a squeeze forming method is generally employed, and specific examples thereof include a vacuum forming method, an air pressure forming method, a vacuum air pressure forming method, and a plug assist type vacuum air pressure forming method. Furthermore, in the case of obtaining a tube- or bottle-like multilayer container (laminate structure) from a multilayer parison (hollow tubular preform before blow), a blow molding method is adopted. Specifically, extrusion blow molding (double-headed, mold moving, parison shift, rotary, accumulator, horizontal parison, etc.), cold parison blow molding, injection blow molding, biaxial stretching Blow molding methods (extrusion type cold parison biaxial stretch blow molding method, injection type cold parison biaxial stretch blow molding method, injection molding in-line biaxial stretch blow molding method, etc.) and the like can be mentioned. The resulting laminate should be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag-making processing, deep drawing processing, box processing, tube processing, split processing, etc. as necessary. Can.

Thickness of multilayer structure (including stretched ones), thickness of EVOH resin composition layer constituting the multilayer structure, thickness of base resin layer and adhesive resin layer, layer constitution, type of base resin, adhesion The thickness of the multilayer structure (including stretched ones) is usually 10 to 5000 μm, preferably 30 to 3000 μm, particularly preferably, although it can not generally be said depending on the type of the conductive resin, the application and the packaging form, and required physical properties. It is 50 to 2000 μm. The EVOH resin composition layer is usually 1 to 500 μm, preferably 3 to 300 μm, particularly preferably 5 to 200 μm, and the base resin layer is usually 5 to 3000 μm, preferably 10 to 2000 μm, particularly preferably 20 to 1000 μm. The adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, and particularly preferably 3 to 100 μm.

Furthermore, the ratio of the thickness of the EVOH resin composition layer to the base resin layer in the multilayer structure (EVOH resin composition layer / base resin layer) is the ratio of the thickest layers when there are multiple layers. The ratio is usually 1/99 to 50/50, preferably 5/95 to 45/55, and particularly preferably 10/90 to 40/60. The thickness ratio of the EVOH resin composition layer to the adhesive resin layer in the multilayer structure (EVOH resin composition layer / adhesive resin layer) is the ratio of thickest layers when there are a plurality of layers. It is usually 10/90 to 99/1, preferably 20/80 to 95/5, particularly preferably 50/50 to 90/10.

The film or sheet obtained as described above, a bag made of a stretched film, a container made of a cup, a tray, a tube, a bottle, etc. and a lid are ordinary foods, as well as seasonings such as mayonnaise and dressing, miso, etc. It is useful as various packaging material containers, such as fermented foods, fats and oils, such as salad oil, beverages, cosmetics, and pharmaceuticals.

EXAMPLES Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to the description of the examples unless it exceeds the gist.
In the examples, "part" means weight basis unless otherwise noted.

Prior to the examples, the following EVOH resin (A) pellets were prepared, and the content of the iron compound (C) contained in the EVOH resin (A) was measured.
EVOH resin (A): an ethylene-vinyl alcohol copolymer having an ethylene structural unit content of 29 mol%, a saponification degree of 99.6 mol%, and an MFR of 3.9 g / 10 min (210 ° C., load 2160 g)

[Measurement of content of iron compound (C)]
A 0.5 g sample of the EVOH resin (A) pellet crushed is ashed (in an oxygen stream at 650 ° C. for 1 hour) in an infrared heating furnace, the ash content is acid-dissolved, and the volume is adjusted with pure water It was a solution. This solution was measured by the standard addition method using the following ICP-MS (ICP mass spectrometer 7500ce manufactured by Agilent Technologies). As a result, the content of the iron compound (C) was 0 ppm in terms of metal.

Example 1
100 parts of the above EVOH resin (A) pellets, 0.01 parts of magnesium stearate (SM-PG, manufactured by Sakai Chemical Industry Co., Ltd.) as the alkaline earth metal compound (B), iron (III) phosphate (III) as the iron compound (C) ) Preheated 0.00230 parts of n hydrate (manufactured by Wako Pure Chemical Industries, 230 weight loss 20.9% by weight) with a plastograph (manufactured by Brabender) for 5 minutes at 230 and then melt-kneaded for 5 minutes , EVOH resin composition was obtained. The obtained EVOH resin composition was pulverized at 650 rpm with a pulverizer (SKR 16-240, manufactured by Sometani Sangyo Co., Ltd.) to obtain a pulverized product. The crushed material was a piece of 1 to 5 mm square.
The metal equivalent content of the alkaline earth metal compound (B) in the EVOH resin composition is 4 ppm in terms of magnesium. Moreover, metal conversion content of an iron compound (C) is 0.1 ppm. The weight ratio of the metal conversion content of the alkaline earth metal compound (B) to the metal conversion content of the iron compound (C) is 40.

Example 2
An EVOH resin composition of Example 2 and a pulverized material thereof were obtained in the same manner as in Example 1 except that the blending amount of iron (III) phosphate n hydrate was changed to 0.00034 part in Example 1. .
The metal equivalent content of the alkaline earth metal compound (B) in the EVOH resin composition is 4 ppm in terms of magnesium. Moreover, metal conversion content of an iron compound (C) is 1 ppm. The weight ratio of the metal conversion content of the alkaline earth metal compound (B) to the metal conversion content of the iron compound (C) is 4.

Example 3
An EVOH resin composition of Example 3 and a pulverized material thereof were obtained in the same manner as in Example 1 except that the blending amount of iron (III) phosphate n hydrate was changed to 0.0034 parts in Example 1. .
The metal equivalent content of the alkaline earth metal compound (B) in the EVOH resin composition is 4 ppm in terms of magnesium. Moreover, metal conversion content of an iron compound (C) is 10 ppm. The weight ratio of the metal conversion content of the alkaline earth metal compound (B) to the metal conversion content of the iron compound (C) is 0.4.

Example 4
EVOH resin composition of Example 4 and Example 4 in the same manner as Example 1 except using 0.01 part of magnesium oxide (Kyowa Mug 30, manufactured by Kyowa Chemical Industry Co., Ltd.) as the alkaline earth metal (B) in Example 1 The crushed material was obtained.
The metal equivalent content of the alkaline earth metal compound (B) in the EVOH resin composition is 60 ppm in terms of magnesium. Moreover, metal conversion content of an iron compound (C) is 0.1 ppm. The weight ratio of the metal conversion content of the alkaline earth metal compound (B) to the metal conversion content of the iron compound (C) is 600.

Example 5
An EVOH resin composition of Example 5 and a pulverized material thereof were obtained in the same manner as in Example 1 except that the blending amount of magnesium stearate in Example 1 was changed to 0.03 parts.
The metal equivalent content of the alkaline earth metal compound (B) in the EVOH resin composition is 12 ppm in terms of magnesium. Moreover, metal conversion content of an iron compound (C) is 0.1 ppm. The weight ratio of the metal conversion content of the alkaline earth metal compound (B) to the metal conversion content of the iron compound (C) is 120.

Comparative Example 1
An EVOH resin composition of Comparative Example 1 and a pulverized product thereof were obtained in the same manner as in Example 1 except that iron (III) phosphate n hydrate was not blended.

Coloring evaluation and thermal stability evaluation of the EVOH resin compositions of Examples 1 to 5 and Comparative Example 1 were performed by the methods described below. The results are shown in Table 1 below.

[Coloring evaluation]
The ground product of the above EVOH resin composition was used as a sample, and the YI value before heating was measured with a spectrocolorimeter SE6000 manufactured by Nippon Denshoku Kogyo Co., Ltd. At this time, the sample was filled in a cylinder having an inner diameter of 32 mm and a height of 30 mm and was used for measurement in a state where it was rubbed. Further, the sample was heat-treated in an oven under an air atmosphere at 150 ° C. for 5 hours, and then the YI value after heating was measured in the same manner. The ratio of the YI value after heating to the YI value before heating was calculated. The larger the value is, the more yellow the resin composition is colored after heating.

[Dynamic viscosity behavior]
The ground product of the above EVOH resin composition was preheated for 5 minutes at 230 ° C. and 50 rpm in a plastograph (manufactured by Brabender) and then melt mixed for 120 minutes. It evaluated by the numerical value which remove | divided the torque of 5 minutes from the measurement start by the torque at the measurement start (0 minute). The lower the value is, the more the viscosity increase during heating is suppressed. Moreover, it evaluated by the numerical value which remove | divided the torque at the time of measurement start (0 minute) by the torque at the time of measurement completion (120 minutes). The higher the value, the more the increase in viscosity with time is suppressed, which means that the dynamic viscosity behavior is excellent.

In Examples 1 to 5 in which the EVOH resin composition of the present invention was used, the ratio of YI values before and after heating was smaller than that of Comparative Example 1 which did not contain the iron compound (C). From these results, it can be seen that the EVOH resin composition for melt molding of the present invention is inhibited from coloring at the time of heating.
Furthermore, in Examples 1 to 5 using the EVOH resin composition for melt molding of the present invention, the dynamic viscosity behavior (5 minutes / 0 minutes) is lower than in Comparative Example 1 which does not contain the iron compound (C), Dynamic viscosity behavior (0 min / 120 min) increased. This means that the viscosity of the EVOH resin composition decreases with time by heating, and it can be seen that long run formability is good.

Although specific embodiments of the present invention have been described in the above examples, the above examples are merely illustrative and are not to be construed as limiting. Various modifications apparent to those skilled in the art are intended to be within the scope of the present invention.

The EVOH resin composition for melt molding according to the present invention suppresses coloration after heating and is excellent in long-run moldability, and therefore various foods, as well as seasonings such as mayonnaise and dressing, fermented foods such as miso, It is useful as various packaging materials such as fat and oil foods such as salad oil, beverages, cosmetics and pharmaceuticals.

Claims (6)

An ethylene-vinyl alcohol copolymer composition comprising an ethylene-vinyl alcohol copolymer (A), an alkaline earth metal compound (B) and an iron compound (C), which comprises the iron compound (C) An ethylene-vinyl alcohol copolymer composition for melt molding characterized in that the amount is 0.01 to 20 ppm in terms of metal per weight of the ethylene-vinyl alcohol copolymer composition. The ethylene for melt-forming according to claim 1, wherein the content of the alkaline earth metal compound (B) is 0.1 to 500 ppm in terms of metal per weight of the ethylene-vinyl alcohol copolymer composition. -Vinyl alcohol copolymer composition. The weight ratio of the metal conversion content of the alkaline earth metal compound (B) to the metal conversion content of the iron compound (C) is 0.005 to 50000. And ethylene-vinyl alcohol copolymer composition for melt molding. The melt-forming ethylene-vinyl alcohol copolymer composition according to any one of claims 1 to 3, wherein the alkaline earth metal compound (B) is a carboxylic acid salt. A pellet comprising the ethylene-vinyl alcohol copolymer composition for melt molding according to any one of claims 1 to 4. A multilayer structure comprising a layer comprising the ethylene-vinyl alcohol copolymer composition for melt molding according to any one of claims 1 to 4.